Rebecca Lea Calderon died peacefully on 21 December 2008 at her home in Chapel Hill, North Carolina, after an 18-month battle with cancer. She was born on 1 November 1955 in Cheyenne, Wyoming. At the time of her death, she was 53 years old. She leaves behind her husband Captain Douglas B. Guthe, Jr, USN (retired), and their 3 children. Rebecca earned her PhD in environmental epidemiology from Yale University in 1986. The world of epidemiology will best remember her for her passion for environmental epidemiology, largely defined by her career with the Environmental Protection Agency (EPA). Rebecca's research focused on effects of waterborne contaminants and waterborne disease outbreaks in recreational and drinking water. In addition to her own research program, Rebecca held several leadership positions at the EPA, most recently as the director of the Human Studies Division in the National Health and Environmental Effects Research Laboratory. As an EPA division director, she advocated for epidemiologic studies of air and water quality and environmental public health indicators. In fact, much of the credit must be attributed to Rebecca for the revitalization of EPA's environmental epidemiology program and for enhancing its prominence, credibility, and contributions. In a regulatory environment that seeks to collect scientifically valid results for the setting of regulations, Rebecca was a leader in gathering information in many disciplines, but always with a human health focus. Rebecca often said epidemiologists “study the right species.” She was keenly aware of the power of human-generated data—how exposures and outcomes observed in human populations could significantly inform decision makers. Her contributions include more than 50 research articles and 17 books and book chapters. She was a member of several professional societies including the American Association for the Advancement of Science, the American Society of Microbiology, and the International Society for Environmental Epidemiology. She was awarded the EPA's Diversity Leadership Award (2001) and the EPA's Gold Medal for the Report on the Environment (2004). She leaves a wealth of work, which will no doubt be carried on by future generations of environmental epidemiologists.